Posted
by
Soulskill
on Wednesday August 22, 2012 @04:13AM
from the and-a-little-safer-from-bloodthirsty-aliens dept.

Hugh Pickens writes "Only four stars, including Barnard's Star, are within six light-years of the Sun, and only 11 are within 10 light-years. That's why Barnard's star, popularized in Robert Forward's hard-SF novel Flight of the Dragonfly, is often short-listed as a target for humanity's first interstellar probe. Astronomers have long hoped to find a habitable planet around it, an alien Earth that might someday bear the boot prints of a future Neil Armstrong, or the tire tracks of a souped-up 25th-century Curiosity rover. But now Ross Anderson reports that a group of researchers led by UC Berkeley's Jieun Choi have delivered the fatal blow to those hopes when they revealed the results of 248 precise Doppler measurements that were designed to examine the star for wobbles indicative of planets around it. The measurements, taken over a period of 25 years, led to a depressing conclusion: 'the habitable zone around Barnard's star appears to be devoid of roughly Earth-mass planets or larger ... [p]revious claims of planets around the star by van de Kamp are strongly refuted.' NASA's Kepler space telescope, which studies a group of distant Milky Way stars, has found more than 2,000 exoplanet candidates in just the past two years, leading many to suspect that our galaxy is home to billions of planets, a sizable portion of which could be habitable. 'This non-detection of nearly Earth-mass planets around Barnard's Star is surely unfortunate, as its distance of only 1.8 parsecs would render any Earth-size planets valuable targets for imaging and spectroscopy, as well as compelling destinations for robotic probes by the end of the century.'"

A lack of planet on a nearby star does not mean there is nothing around the star

There might still be fragments of ice / rocks / whatever that humankind can use to construct an artificial planet of some kind

Plus, the lack of existing planet means we get to create one, with our own design

Yea, make our own planet. Simple! This got modded 5 Insightful? Why not make another Earth in our own solar system? It would be way easier to do it here where all the resources are, instead of in a distant solar system. Or even easier, crash asteroids from the asteroid belt into Mars to create an Earth size planet. Why don't we do it? Because it would be freakin' impossible for any beings without near God-like technological powers.

"Why don't we do it? Because it would be freakin' impossible for any beings without near God-like technological powers.

People not so long ago would have said that about many of the things we take for granted today. Try telling someone a couple of hundred years ago that we'd build aircraft that could carry hundreds of people at 2/3 the speed of sound to the other side of the planet in a few hours, or that we'd be able to pull a small device out of our pockets and talk instantly to someone anywhere on earth, or that we'd be able to send a sophisticated robot to Mars to explore and conduct science experiments. Creating an artificial planet isn't essentially that hard, it just requires a level of technology beyond where we're currently at. Get to a stage where you can send out self-replicating robots to collect and process asteroids for you, for example, and it might look a bit less daunting. And there's no particular reason to believe that we won't eventually develop such technologies.

One thousand years ago, the peak of technology was a powder that would explode when ignited, that could propel a small projectile in a general direction a few hundred feet. Today, the peak of technology is dropping a laser-armed nuclear-powered semi-autonomous wheeled laboratory from a rocket-powered flying crane onto a precise target from 150 million miles away.

By the time we have the capability to load up humans and send them 1.8 parsecs away before they (and any descendents) die, we might just have the technology to build an artificial planet, or at least a large structure capable of artificial gravity, a self-sustaining ecosystem, and harvesting materials from whatever asteroids are nearby. It does not need to be as big as the Earth or support as large a population, but it'll do for a while until technology improves further.

You want some faster than light travel with that?Or perhaps telekinesis?

Artificial gravity can easily be implemented with acceleration. Pretty much every amusement park out there have a "large" structure capable of artificial gravity. They usually create a gravity-like force out from the center but sometimes they create a transient gravity-like force, either upwards or downwards from earth to increase or decrease the real gravitational force you fell form the planet.

Faster than light travel is a bit harder since traveling at light speed isn't supported by current models. If the

Structural engineering (and the related chemistry, metallurgy, and industrial engineering) technology will have to improve, of course, but it is reasonable to build a large spinning wheel as a habitat around a central weightless work area. It doesn't need to be nearly as much as Earth's gravity to be useful, and the subsequent generations that spend their whole lives on the craft will adapt (mentally first, then ever-so-slowly physically) to the altered environment.

Now that is within the realm of possibility, as long as it's at a small enough scale that it's doable. We can probably work around how this differs from gravity (your head being lighter than your feet, coriolis effects, curvature going the wrong way), or adapt.

Artificial gravity as in Star Trek, on the other hand, is not, at present, something it's even worth working towards. If we get a new set of physics, then we can revisit that -- just like human flight needed a new set of physics before it could beco

And that's what probes are for, which is a good way to test the travel capability. Of course, even if we sent a probe today, we're talking a few generations before useful data is returned, and our probe technology isn't really good enough to scan a whole solar system for asteroids yet... so now's a good time to work on picking promising stars, confirming or ruling out suspicions, and exploring our own solar system. Heck, maybe we can get a viable small fusion reactor working productively, then we just have

Doesn't sound like you appreciate the difficulties of doing an interstellar probe. It's not like silicon chips, in which we've seen astounding improvements. We simply can't do it, not now, and probably not in the next 20 years or even 100 years.

Currently, our fastest escaping probe is Voyager 1, at about 17 km/s relative to the sun. At that rate, a probe will need about 70000 years to reach Alpha Centauri. Suppose the velocity we can give probes improves by a factor of 100, which is assuming a lot. (For one thing, gravity assists would be of little value.) That's still 700 years. We have no experience making machines that can last that long. Our civilization might not last that long. We need perhaps 1000 times the velocity, then we're talking only a 70 year wait.

To achieve 1000 times the velocity is not a matter of 1000 times the fuel, it's 1000^2 times the fuel. It's even worse than that, if the probe has to carry its fuel. No matter how we accelerate the probe-- whether with on board ion drives, nuclear bombs, light sails, or something else-- that's such a huge amount of energy that none of these ideas are even remotely feasible. That means it will have to be slower, which puts us back to the problem of how to build something that can last the 1000 plus years such a trip will take. There are many other problems, such as communication, but the primary one is simply the distance. I wouldn't hold my breath for science fantasy either. It's not at all likely we will invent warp drive or some other means of FTL travel.

Easier said than done. There would be a lot of new science required just for planet terraforming that does not exist today. An example, how to make the planet's core more active to support tectonic plates so that the rock material from crashing asteroids into the planet get recycled into larger rocks. Then there is calculating the right amount of liquid water needed to sustain the planet and somehow transport it whether its crashing comets into the planet. Altering the planet's rotation if its tidally locke

Seriously, I can't think of anyone else who believe that humans will create planets. No, this is not flamebait or trolling - it really is the only ones I can think of that might see this as a possibility, although not while still human.

And if there really are someone delusional enough here to think that we could create our own planet while being mortal humans, you really need to think about the scale here. It's not just huge, it's immense. We only scratch the surface of this planet.If we found Mount Everest sized rocks (~3x10^15 kg) in a solar system, we would need around 2 000 000 000, that is 2 milliard (or billion for those who use the short system) of them to create a planet with Earth's mass (~6x10^24 kg). Imagine the power and time needed to move one Mount Everest. Each Chomalungma sized rock is about 28 milliard (or billion in the short sytem) times the weight of the space shuttle.

And we're not just talking scale here. Think about how you would adjust the orbital speed of the mass you assemble so it would stay in orbit as you add to it. Or how to cool it down from all that kinetic energy -- how long did it take Earth to cool down? Or how to survive the flares of Barnard's Star?

Niven and Lucas make great space operas. But we have to admit to some limitations. Come back in a few million years, and whatever species have descended from us may have a different opinion. But us? No, we have no chance.

Yeah I mean what's with people who think humans can fly? There are just things that humans were not meant to do!

Everything is impossible until you figure out how to make it possible...

This isn't just a technical issue, unless Newton, Carnot and Einstein were all wrong in pretty radical ways.Scoffing at building a planet is more like scoffing at someone who says he can eat the moon. It's not just a question of getting and preparing the moon - there's not enough time for it to happen in.

The idea of flight still applies. Flight of something that has all of its thrust propelling it forward seems impossible until we understood how a wing can produce lift. Yes the necessary forces to produce a planet in a sane amount of time are quite a bit different from that of a wing and may not exist at all. However we can't assume we know everything about how the universe works since our theories keep getting proven wrong (or incomplete). Unless we understand that there may be forces to the universe we don't know about yet, we will not recognize them when we finally see them.

Everything is impossible until you figure out how to make it possible...

It's not impossible -- it's just really, really improbable given the current state of our energy and propulsion technology, and there's not much big propulsion tech on the horizon that would seem likely to change that anytime soon. VASIMR is pretty promising for small manned spacecraft (and even more so for large robotic spacecraft) but it's basically in the realm of ion engines -- high efficiency, long run times, but relatively small thrust even compared to fuel/oxidizer engines. Even Orion-style propuls

No disagreement there but we went a really long time with nothing more than animal propulsion before we figured out other means. If humanity can survive for a long time into the future the the possibility exists of a similar drastic increase from present capabilities. Probability is likely against it but I'd rather shoot for the moon (or making one) and still be happy if I can at least get off the ground:)

Planet? Not so hard really, use well targeted nuclear explosions to adjust asteroid orbits just enough to induce collisions... a lot of collisions.

Oh, you mean a habitable one? That's going to be a tall order. A planet wouldn't be so hard to do, you just need to put enough matter together and gravity will do the rest... in a few hundred million years. The habitable part is much more tricky. You need water, plate tectonics, magnetic field, inert atmosphere, ozone layer, etc.

Niven and Lucas make great space operas. But we have to admit to some limitations. Come back in a few million years, and whatever species have descended from us may have a different opinion. But us? No, we have no chance.

We are hardwired for optimism, for better and for worse. And future milestone breakthroughs are very hard to predict. Some predict an accurate simulation of the human brain is only several years away. Strong AI shouldn't be too far off after that. Strong AI will expand the sphere of whats possible, technologically. But we human beings are most defintely very primitive. IMO, we have never possessed the type of ethical wisdom, nor moral courage that would allow our species to survive well into the future.

Interstellar travel will probably give us that Near God-Like technological power that you seem to think will be missing. Getting there will be much harder then moving a few rocks around. Though doing it in our own solar system might be considered dangrous. Changing the existing set of gravity wells could cause any number of problems, but who cares if it's an uninhabitable solar system.

Um, no. A planet isn't just "a few rocks". The scale is immense, and we're bound by the laws of physics and thermodynamics.

Never mind where we would get the energy to accelerate and decelerate such masses from, it would likely take thousands of millions of years to assemble those "few" (thousands of millions) gargantuan rocks and have the new planet cool down enough to be ready for terra-forming.

Getting there isn't even in the same fantasy as creating a planet. There are orders of orders of magnitude dif

What is your resistance to using the work billion? It isn't a dirty word.

Also, I agree with you mostly on this. They only way I can see people making a planet is by making self replicating robots that can mine the universe for energy and minerals and have them do all the work. If they can build themselves expoentially and are somewhat networked they could be "told" to go forth and multiply and make us a planet. It still wouldn't be a weekend endevour though.

By the time we have the technology to smash together enough rocks that it can hold an atmosphere with its natural gravitational force, we won't need to live on a rock with enough natural gravitational force to hold an atmosphere.

That godlike amount of effort could be spent doing something more practical.

If we ever have the technology to create our own planet, why wouldn't we do it right here in our own solar system? There's plenty of extra material floating around. Not to mention, if we have the tech and ability to create a planet we probably also have the ability that we could just push Mars closer or Venus farther out to get them into the habitable zone.

There might still be fragments of ice / rocks / whatever that humankind can use to construct an artificial planet of some kind

You've completely missed the point. NASA has a hard-on for searching for signs of life on other planets, and an "Earth" in the next solar system would be a damn near perfect place to find life, or otherwise lend credence to the opposition (that says life is unique to Earth, or at least not the oh-so-common scenario which most contemporary astronomers claim that it is).

A lack of planet on a nearby star does not mean there is nothing around the star

And, even more to the point, a lack of a planet larger than ten times the Earth's mass in an Earth-like orbit, or two times Earth's mass in a close-in (ten day) orbit says nothing about the presence or absence of Earth- mass planets, unless you have a well-accepted theory showing that systems with Earthlike planets must also have Jupiter-like planets, which is a theory we don't have.

And, worse, the mass detection limits are limits on m*sin(i)-- if the orbits are inclined, the planet masses that couldn't be detected would be even larger. (in the limit, if the orbit is face on, it wouldn't have detected planets regardless of how massive they are)

Overall conclusion: This puts limits on planets around Barnard's star, but did not have the ability to detect, and thus did not rule out, Earth-mass planets.

There might still be fragments of ice / rocks / whatever that humankind can use to construct an artificial planet of some kind

The point is that there is nothing in the "life zone", where you find liquid water, so pretty unlikely there is any life in the system.Which is about the only thing that would justify the gigantic cost of going here.

If we're going to build habitats from scratch, we have plenty of rocks in our own system, asteroids, moons, then the Kuiper Belt. As long a we can hold off from killing ourselves, we could house trillions in this system in the next few thousand years.

There is an interesting aspect towards Science Fiction... The fact that it is Fiction.fiction [fik-shuhn] Show IPAnoun1.the class of literature comprising works of imaginative narration, especially in prose form.2.works of this class, as novels or short stories: detective fiction.3.something feigned, invented, or imagined; a made-up story: We've all heard the fiction of her being in delicate health.4.the act of feigning, inventing, or imagining.5.an imaginary thing or event, postulated for the purposes of

Hmmm, and how much science fiction has become true within a century or two of it being written? Traveling to moon? Did that. Created giant subs capable of traversing the world's oceans? Did that. Went to Mars? We're pretty close. Cybernetics? Robotics? The author that came up with those lived to see them start to become real.

And hard to envisage habitable plants remaining stable for sufficiently long periods of time for complex life to evolve. Though if you're looking for somewhere to put people, planets without existing life are a much better bet.

What about Alpha Centauri? I suppose the binary nature of the star system could make it hard to detect any planets there.

No, since we know of the existence and orbital period of the two bodies, all it takes is a little extra number crunching to removes those wobbles from the data. It's pretty straightforward signal analysis. That the frequency of those wobbles will be different from the frequency of planetary wobbles just makes it easier.

How big a telescope would need to be, in order to be able to find streetlights on a planet 10 light years away, either by looking for an artificial spectrum, or for a frequency of the order of 50Hz, assuming a continent-wide synchronised AC power supply.

Assuming you just want a big telescope that can resolve something on the scale of a streetlamp, 10 light years away...

We'll need the small-angle formula and the Raleigh Criterion. The first gives us the angular size of the streetlight; the second gives us th

For a moment there, I thought you meant on the other side of the moon from us, rather than from the base. I was already to go "nooooo, that'll crash it into the Earth, you fool!" Then I realised. And posted anyway. Ah well.

For a moment there, I thought you meant on the other side of the moon from us, rather than from the base. I was already to go "nooooo, that'll crash it into the Earth, you fool!" Then I realised. And posted anyway. Ah well.

yes, that's the ridiculous part of the "nuclear powered moon-ship" plan.

I read a short story once where (based on my very limited memory of the story) a planet had lost its sun somehow and was near absolute zero on the surface. A small group of survivors lived underground in what they called 'the nest' and actually went to the surface periodically to gather some oxygen 'snow' to bring back down to the nest and boil into breathable air.

The barycenter of sun-earth is only 300 miles from the middle of the sun.

Keep in mind that Barnard's star is only about a seventh of the sun, and much cooler, so the habitable zone is much closer. An earth sized planet in the habitable zone would have a much larger impact on Barnard's Star than Earth does on Sol.

Now I'm seriously worried. Every time I played Masters of Orion 2 and I got situated in an area where the closest habitable planet was far away I always got my ass kicked by some civilization that was able to expand quickly. Our only hope is to start developing Deuterium fuel cells, and quickly!

6 years is a little long to wait for control instructions. If we sent a probe, it'd either be 100% automated (not likely if we ever want to see it again) or we'd have technology to travel there faster or communicate faster. In the case of travel faster we would simply send humans. Why would we send a probe instead?

We all love the stories, but I'm curious what the last twenty years have suggested as we've become more detailed and accurate with some of our modelings and scientific theories. I *am* wondering what the actual state of science is currently. FTL is proposed to be impossible, but has science concluded that things like wormholes can actually function the way sci-fi suggests and frequently makes use of? Are there any physical properties that don't violate FTL laws, but work around them? Or have we decided that

I don' t think the Earth could provide the energy needed for interstellar flight as we know it, but in principle the only energy needed to move between (4 dimensional) points A and B is the difference in potential energy between the two points. In practice the only method of acceleration in space we have is to eject 4-momentum in the opposite direction, permanently losing that energy.

We could do a lot if there were some way of manipulating gravity, e.g. a gravitational lens could pull ships about without wa

However, the great advantage of artificial gravity would be reactionless drives. That means we wouldn't have to carry around massive amounts of fuel that we're just going to eject from a big nozzle to keep us moving. If you were able to generate artificial gravity, you could have a nice compact energy source like a fusion or antimatter plant and manipulate space-time to create a gradient.

Send a probe to another star by the end of the century, really! I'd like what they are smoking. At current technology, that would take about 8,000 years to get there. Using space sales, that might be reduced to 3,000 years. Using a nuclear pulse engine, that could be reduced to 300 years. Of course, they better develop deflector shields, too, because at the velocity of a nuclear pulse engine, a small particle has the potential to destroy the probe given the kinetic energy involved and as we all know, sp

If a solar system has only one thing in it and that thing is mostly just relatively undifferentiated hydrogen, that's going to be less interesting that a solar system with a bunch of things in it. (Regardless of any ideas about colonizing or anything else.) It's certainly still possible that there is something fascinating in that solar system, but at the moment, it would have to be something we still can't detect, so it's hard to get as excited about. Planets are fascinating things. They have interesting geology and interesting compositions. They also imply that there is enough mass for things smaller than planets, like comets and asteroids as well.

Yeah, but that is not the argument in this story, the argument is not that there are no planets there, the argument is that there are no Earth size (or larger) planets are not found within the 'habitable zone'.

This doesn't mean there are no planets, there are no planetoids, there are no comets, there is nothing there. It means there are no planets like this one or bigger within the 'habitable range', which is another thing that we make various assumptions about.

When the wise man points at the moon, the naive looks at the stars behind. Go to the Moon, extract water, create an atmosphere, grow plants. Nobody says it's easy. But the whole is likely to take less time than to go to a "near" star and find a "livable" planet...

The advantage of Venus over Mars is that is already has abundant oxygen in the atmosphere, just in a different state than we need it. It's also a lot closer to the sun, so solar power is much more efficient. I wouldn't expect non-domed cities anytime soon, but the materials and resources are there to fuel a domed or underground colony.

Yes, except the atmospheric pressure at the surface is gigantic and the solar energy that reaches the surface makes it about as bright as Mars. I'd also talk about the sulfuric acid rain, but due to the pressure, it actually doesn't rain below a certain level of the atmosphere.

Venus *might* be habitable if we can strip off most of the greenhouse gasses and reduce the pressure, but it also doesn't have plate tectonics, its whole crust basically inverts when it is time to release heat from its mantle, so tha

We still need a fallback planet. We could keep this one in pristine shape and the Sun will simply eat it a couple of billion years from now. Of course, something like a massive collision or interactions with other stars could also well happen well before that.

Never fear, we'll need to clean this planet up long before we can even think about colonization, but the relative costs of space exploration are actually pretty tiny if you look at the budgets, there's no need to cancel the manned space program to cl